The headline of this column does not, however, refer to the Annual General Meeting of the Royal Horticultural Society (RHS). Rather, it refers to the RHS Award of Garden Merit (AGM) which is intended to help gardeners choose the best plants for their gardens – and there are a well-nigh unbelievable 229,000 results to Googling ‘RHS AGM.’ “You may well have seen the AGM logo,” the first of these hundreds of thousands begins. “A cup symbol on a plant’s label shows that it has earned the AGM – it's our seal of approval that the plant performs reliably in the garden.” So, what is the AGM? The RHS’s answer is to ask the enquirer another question. “With more than 75,000 plants available in RHS Plant Finder alone, how can you tell which plants are best for all-round garden value?” And then comes the answer: “The AGM is intended to help gardeners make that choice, and is only awarded to plants that are: excellent for ordinary use in appropriate conditions; available” … I like that one! … “good constitution; essentially stable in form and colour; and reasonably resistant to pests and diseases.” Fair enough, even if I almost certainly can’t complain if my local garden centre doesn’t have available a variety which I have read has earned the AGM. And this is very possible, given that plants of all kinds can be considered for the AGM, including fruit and vegetables; that the list currently includes more than 7,500 plants; and that new awards are made each year to keep the award lists as up to date as possible.
Elsewhere on the plethora of RHS web sites, we find the Lists of Award of Garden Merit to camellias, clematis, dahlias, dianthus, flowering cherries, magnolias, maples, narcissus, rhododendrons, roses, sweet peas and tulips, to name only the flowering plants. Within each and every plant family list are details of the varieties which have been deemed to merit the AGM, constantly changing as new awards are granted and old awards rescinded. It may well be that the single most useful feature of these many pages of lists is a footnote which reads: “Key to hardiness ratings: H1a tropical: heated greenhouse; more than 15C / H1b subtropical: heated greenhouse 10°C to 15°C / H1c warm temperate: heated greenhouse; 5°C to 10°C / H2 tender: cool or frost-free greenhouse; 1°C to 5°C / H3 half-hardy: unheated greenhouse or mild winter; -5°C to 1°C / H4 hardy: average winter; -10°C to -5°C / H5 hardy: cold winter; -15°C to -10°C / H6 hardy: very cold winter; -20°C to -15°C / H7 very hardy; less than -20°C.” From that one footnote, the casual gardener can learn that AGM-winning plants really must come within categories H3 and H4 to survive a Falkirk winter outdoors. Now that’s worth knowing and might save one a pound or two!
There is a wealth of information online at ‘RHS AGM.’ Reiterating the RHS’s words, “Perhaps more than anything else the AGM will help those who wish to take advantage of the knowledge of professional gardeners when choosing plants.” I’ll drink to that!